This work will involve investigations into the molecular mechanisms whereby insulin regulates glycolysis. The principal approach will involve studies on isolated muscles and also on diabetic animals. The studies are designed to further clarify the mechanism whereby insulin regulates intracellular pH, and to obtain evidence that it is a change in intracellular pH (along with other ionic changes) which mediates the effect of insulin upon glycolysis. Studies will be conducted of the regulation of intracellular free Mg ions and investigations will be conducted to determine if insulin affects this parameter. The requirement for CO2/HCO3 in Ringer for insulin to affect carbohydrate metabolism will be investigated. Diabetic animals will be studied to determine the mechanism whereby the diabetic state results in an increase in intracellular Na ion and decrease in ATP in rat soleus. The effect of insulin upon the rate of oxygen uptake by isolated skeletal muscles and also by intact animals will be studied. The experiments will be conducted on frog skeletal muscle (sartorius) and upon rat skeletal muscle (soleus) with the muscle from one leg serving as a paired control for the other. Intracellular pH will be determined by the use of DMO-14C (14C 5, 5-dimethyl 1-2, 4-oxazolidinedione) as well as pH sensitive glass microelectrodes. Glycolytic rates will be followed by determining lactate with LDH and NAD. 3H-ouabain will be used to determine the number of sodium pump sites and to determine the affinity of these pumps for ouabain. The diabetic state will be investigated using genetically diabetic animals as well as animals made diabetic by injections of streptozotocin.